There is a strong bi-directional relationship between sleep deprivation/disturbance and depression. Although disturbed sleep is associated with psychiatric disorders and is traditionally considered to be a symptom of depression,9 research suggests that the relationship between sleep changes and mood disorders may work in the other direction as well.10 In addition to being a symptom, disrupted or a lack of sleep may also be a causal factor that contributes to the development of mood disorders.10,11 Chronic insomnia was found to increase the odds ratio of developing depression in several longitudinal studies.9,12 Alterations in sleep patterns are associated with depression, a fact which has been reported in the literature for over three decades.11,12 Additionally, certain sleep breathing disorders have a strong association with depression. Obstructive sleep apnoea syndrome is significantly associated with an impairment in cognitive function due to sleep disturbance and subsequent daytime sleepiness.13 Peppard et al. found a dose-response association between sleep-related breathing disorders and depression.14 This finding might be attributed to frequent awakening due to the sleep apnoea, in addition to repeated hypoxic stress to the brain as a result of desaturation.14

Contrarily, acute sleep deprivation has been long reported to be beneficial in treating depression. An early study revealed that a single night of sleep deprivation had an antidepressive effect.15 Therapeutic sleep deprivation was performed either as total sleep deprivation or with selective non-rapid eye movement (REM) sleep deprivation.16,17 The efficacy of either method has not yet been well investigated, although the impression received suggests that total sleep deprivation is superior to the selective technique.15 Nonetheless, therapeutic sleep deprivation is not free of side-effects. Depressed individuals may experience increases in impulsiveness and drive.17 In addition, they would also suffer from excessive daytime sleepiness, which might be difficult to distinguish, especially in non-responders, with a worsening of the depressive symptoms.17

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4318605/

1) take something complicated

2) oversimplify it

3) ???

4) PROFIT

(the "???" is "publish a meaningless paper")